Título

Clustering, Bias and the Accretion Mode of X-ray selected AGN

Autor

Manolis Plionis

Nivel de Acceso

Acceso Abierto

Resumen o descripción

We present the spatial clustering properties of 1466 X-ray selected AGN compiled from the Chandra CDF-N, CDF-S, eCDF-S, COSMOS and AEGIS fields in the 0.5−8 keV band. The X-ray sources span the redshift interval 0 < z < 3 and have a median value of ⁻z = 0.976. We employ the projected two-point correlation function to infer the spatial clustering and find a clustering length of r₀ = 7.2 ± 0.6h⁻¹ Mpc and a slope of γ = 1.48 ± 0.12, which corresponds to a bias of b(⁻z ) = 2.26±0.16. Using two different halo bias models, we consistently estimate an average dark-matter host halo mass of Mₕ ≃ 1.3(±0.3) × 10¹³h⁻¹Mꙩ. The Xray AGN bias and the corresponding dark-matter host halo mass, are significantly higher tan the corresponding values of optically selected AGN (at the same redshifts). The redshift evolution of the X-ray selected AGN bias indicates, in agreement with other recent studies, that a unique dark-matter halo mass does not fit well the bias at all the different redshifts probed. Furthermore, we investigate if there is a dependence of the clustering strength on X-ray luminosity. To this end we consider only 650 sources around z ∼ 1 and we apply a procedure to disentangle the dependence of clustering on redshift. We find indications for a positive dependence of the clustering length on X-ray luminosity, in the sense that the more luminous sources have a larger clustering length and hence a higher dark-matter halo mass. In detail we find for an average luminosity difference of δlog₁₀ Lₓ ≃ 1 a halo mass difference of a factor of ∼3. These findings appear to be consistent with a galaxy-formation model where the gas accreted onto the supermassive black hole in intermediate luminosity AGN comes mostly from the hot-halo atmosphere around the host galaxy.

Editor

Monthly Notices of the Royal Astronomical Society

Fecha de publicación

28 de septiembre de 2012

Tipo de publicación

Artículo

Versión de la publicación

Versión aceptada

Formato

application/pdf

Idioma

Inglés

Audiencia

Estudiantes

Investigadores

Público en general

Sugerencia de citación

Koutoulidis, L., et al., (2012), Clustering, Bias and the Accretion Mode of X-ray selected AGN, Monthly Notices of the Royal Astronomical Society, Vol. 428(2):1-14

Repositorio Orígen

Repositorio Institucional del INAOE

Descargas

249

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